1. Field of the Invention
The present invention relates to an autofocus adjustment device and method for a camera, a video camera, and the like capable of executing proper predicted driving when the direction of movement of the photographic subject reverses.
2. Discussion of Related Art
In the past, a camera having a focus detection device tracks a moving photographic subject by predicted driving of the photographic lens assembly when the photographic subject is moving and prohibits driving of the photographic lens assembly if predicted driving is not appropriate (Japanese Unexamined Patent Publication Hei 1-285908).
A conventional camera capable of performing predicted driving of the photographic lens assembly can continuously shoot a photographic subject passing in front of the photographer. In this case, the locus of the movement of the photographic lens assembly operates in a manner illustrated by FIG. 1. The dotted line in FIG. 1 denotes the starting time of electric charge accumulation (I1, I2, . . . , I5), the broken line denotes the time of exposure (E1, E2, . . . , E4), and the blocks in the accumulation/calculation line represent the period of time during which the electric charge accumulation and the focus detection calculation are performed (C1, C2, . . . , C5).
The conventional camera that is capable of performing projected driving prohibits projected driving after a moving subject reverses the direction of its movement. Moreover, because projected driving is not executed unless a specified number of focus detections is performed, much time elapses until projected driving occurs during the time of continuous photography. Therefore, this type of camera often suffers from blurred pictures and a lack of an intersection of the photographic lens assembly position and the photographic subject position, that is, an inability to focus the photographic lens assembly at the time of exposure for some time after reversal of the direction of the movement of the photographic subject.